Some new fixes/ehancements:
* Now it's possible to do matrix * 3D point (thanks to Murkle)
* When mouse is clicked on xOy plane, create free 3D point.
* Button for show/hide xOy plane in 3D view style bar.
* Intersection tool for line/line, line/conic, conic/conic should work better with 2D/3D objects/view
* Euclidian view for plane : same view orientation as "view in front of"
* You can now choose an object which is behind another, by right-clicking over it. For example, you can easily select the hexagon that is inside the cube in the file below: right-click on over the hexagon, then e.g. "face BCGF" is first selected, but you can select the hexagon at the bottom of the popup menu. This should lead to much easier e.g. set properties, etc. You can also select the cube ("Prism e") itself to e.g. change the whole colour of it.
(Note that there is a little bug on display - should be fixed quickly.)